Method and apparatus to provision network routes

ABSTRACT

A method to provision routes in a network having a plurality of nodes includes receiving a designation of a primary source node, determining possible destination nodes from the designated source node and outputting information indicating the possible destination nodes. The method further includes receiving a designation of a destination node from among the possible destination nodes and updating information regarding optical characteristics based on a route from the source node to the designated destination node and outputting information related to the updated optical characteristics.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. ProvisionalApplication No. 60/932,840, filed Jun. 1, 2007, which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to provisioning network routes and, moreparticularly, relates to interactively provisioning network routes.

2. Description of the Related Art

In a communication network having a plurality of interconnected nodes,there may be multiple routes that data can traverse from a source nodeto a drop node (i.e., a node where the data will be used). There may bea direct link between the source node and the drop node, and/or theremay be a plurality of routes from the source node to the drop node viaone or more intermediate nodes. Particular routes between a source nodeand each drop node are provisioned (i.e., established) so that networkequipment know how to route data to a particular drop node. Theinformation regarding provisioned routes can be stored in a routingtable that a node uses to determine the appropriate route to send orforward data (the routing table can be stored in a computer programmemory, for example), or the network can be engineered to ensure thatdata flows in a certain way (i.e., network equipment can be wired orcabled to constrain the flow of data in a specific direction).

Various techniques are known for automatically provisioning networkroutes to optimize transmission characteristics. For example, techniquesare known that determine the shortest distance between nodes, the fewestnumber of links to be traversed between nodes, and the minimum costroute (where a weighted value or “cost” is assigned to each networklink). However, these techniques do not work well when the number ofpossible routes becomes large, or special conditions exist that are notcharacterized by a weight or cost. The number of routes may be large dueto the network type, e.g., a mesh network in which nodes may be linkedto multiple other nodes, or due to the type of data traffic for whichroutes are being provisioned, e.g., broadcast traffic where routes mustbe provisioned from a source node to each of multiple drop nodes.Further, in the case of broadcast data, a secondary (i.e., backup)source node is often used, and routes must be provisioned from thesecondary source node to each drop node, preferably using diverserouting (i.e., routes that differ from the routes used from the primarysource node).

One approach to achieve diverse routing in a mesh network has been todivide the mesh network into plural ring networks. In a ring network,each node is linked to just two other nodes, so traffic received on onelink is always sent out on the other link, and vice versa. Diverserouting is achieved within each ring by routing the unidirectionaltraffic in opposite directions along the ring. However, this approach isnot optimal for a mesh network, because some of the nodes might get thesame traffic flow more than once, and therefore some of the links may beoverutilized.

SUMMARY OF THE INVENTION

According to a one aspect of the present invention, a method toprovision routes in a network having a plurality of nodes includesreceiving a designation of a primary source node, determining possibledestination nodes from the designated source node and outputtinginformation indicating the possible destination nodes. The methodfurther includes receiving a designation of a destination node fromamong the possible destination nodes and updating information regardingoptical characteristics based on a route from the source node to thedesignated destination node, and outputting information related to theupdated optical characteristics

According to another aspect of the present invention, a method toprovision routes in a network having a plurality of nodes includesreceiving a designation of a source node, determining possibledestination nodes from the designated source node, and outputtinginformation indicating the possible destination nodes. The method alsoincludes receiving a designation of a destination node from among thepossible destination nodes, determining possible routes from the sourcenode to the designated destination node, and outputting informationindicating the possible routes. Further, the method includes updatinginformation regarding optical characteristics for each possible routefrom the source node to the designated destination node, outputtinginformation related to the optical characteristics, and receiving adesignation of a route from among the possible routes to the destinationnode.

According to a further aspect of the present invention, an apparatus toprovision routes in a network is provided that includes a memory tostore information regarding a plurality of network nodes and linksconnecting network nodes, a display to display information regarding theplurality of network nodes and the links connecting the network nodes,and a user interface to input user designations. The apparatus alsoincludes a processor to control the apparatus to (i) receive adesignation from the user interface indicating a source node, (ii)determine possible destination nodes from the designated source node,(iii) display information regarding the possible destination nodes, (iv)receive a designation from the user interface indicating a destinationnode selected from among the possible destination nodes, (v) updateinformation regarding optical characteristics based on the designateddestination node and the stored information regarding links betweennetwork nodes, and (vi) display information related to the updatedoptical characteristics.

According to yet another aspect of the present invention, a computerprogram embodied in a computer-readable storage medium is provided. Thecomputer program includes program code to control an apparatus toreceive a designation indicating a source node among a plurality ofnetwork nodes, determine possible destination nodes from the designatedsource node, and display information regarding the possible destinationnodes. The program code further controls the apparatus to receive adesignation indicating a destination node selected from among thepossible destination nodes, update information regarding opticalcharacteristics based on the designated destination node and storedinformation regarding links between network nodes, and displayinformation related to the updated optical characteristics.

According to still another aspect of the present invention, a method toprovision routes in a network having a plurality of nodes includesdesignating a primary source node, designating a destination node in adisplay of possible destination nodes from the designated primary sourcenode, and designating a node as a regeneration node, based on displayedinformation concerning optical characteristics updated based on thedesignated destination node.

These and other aspects of the present invention will be described infurther detail below, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a display of a network having a plurality of nodes,to which an example embodiment of the present invention may be applied.

FIG. 2 illustrates a display of a network having a plurality of routesdesignated for a primary source node and a secondary source node.

FIG. 3 illustrates an example embodiment of a process to provisionroutes in a network according to the present invention.

FIG. 4 illustrates another embodiment of a process to provision routesin a network according to the present invention.

FIG. 5 illustrates an example embodiment of an apparatus to provisionroutes in a network according to the present invention.

FIG. 6 illustrates an example embodiment of a process followed by a userto provision routes in a network according to the present invention.

DETAILED DESCRIPTION

An example embodiment of a process to provision network routes fordual-source unidirectional broadcast data will be explained with respectto FIGS. 1 to 3. This example embodiment can be applied, for example, toa video broadcast. In a video broadcast, the video signal originates ata particular node, which will be referred to herein as the primarysource node. The video signal must be routed to every drop node in thenetwork, i.e., every node where the video signal will be used. Further,to minimize outages in the event of a problem with the primary sourcenode, a backup source for the video signal may be used, which will bereferred to herein as the secondary source node. Those skilled in theart will appreciate from the following description that the presentinvention is not necessarily limited to video data, dual-source data, orbroadcast data.

FIG. 1 illustrates a display 5 showing a network 10 having multiplenodes, numbered S1 to S10. Display 5 also includes a drop-down menu 15,soft buttons 20, 30, 40, and 50 for respectively designating a node as aprimary source, a secondary source, a drop node, and a regeneration node(i.e., a node where the data signal is regenerated), and a display area60 for displaying information related to optical characteristics.

Some of the nodes in network 10 include network equipment that can serveas a drop node, i.e., a node where the data can be used. On the otherhand, some of the nodes are so-called “glass” nodes. Glass nodes do notcontain network equipment that allow the node to serve as a drop node.For example, a glass node may merely include a signal repeater, a patchpanel, or some other interface connecting two different transmissionlinks or different types of transmission links. In FIG. 1, nodes S1-S3,S5, and S7-S10 are nodes having network equipment, as indicated by thelabel “NE” at those nodes, and nodes S4 and S6 are glass nodes. Further,node S10 is referred to as a spur node, because it is connected to onlyone other node.

As shown in FIG. 1, there are links interconnecting various nodes. Inthe example embodiment these links are optical fiber links, but thelinks are not limited to optical fibers. The links are designated usingthe numbers of the nodes they connect. For example, the link betweennode S1 and node S2 is designated L1/2, and the link between node S3 andnode S4 is designated L3/4.

Data is routed from the primary source node to one or more drop nodes.In this example embodiment, node S1 will be designated as the primarysource node. Since this example embodiment illustrates provisioningnetwork routes for broadcast data, all other nodes having networkequipment will be drop nodes in this example. So, in this exampleembodiment, a route will be provisioned from node S1 to each other nodehaving network equipment, namely, nodes S2, S3, S5, and S7-S10.

A user can designate a primary source node using a user interface suchas a mouse. In this example embodiment, display 5 includes “soft” optionbuttons 20 for designating a primary source node and 30 for designatinga secondary source node. The user can select button 20 with the mouse,and then move the cursor over node S1 and click on it to designate nodeS1 as the primary source node. Preferably, node S1 will be highlightedor colored on display 5.

Routes are provisioned in increments of a “hop,” where a hop is a routebetween two nodes having network equipment that does not pass throughanother node having network equipment (but it may pass through a glassnode). Each hop routes the data signal from a source node to adestination node. (While there is only one primary source node, i.e.,the original source of the data signal, many network nodes function as a“source” node for a particular hop.) Thus, a destination node, as usedherein, refers to another node having network equipment that can bereached from the currently designated source node in one hop. Putanother way, a destination node is a node having network equipment thatis linked to a particular source node either directly or via one or moreglass nodes. A destination node can be a drop node, where the datasignal is used, or simply a pass-through node that passes the datasignal on to other nodes. Whether the destination node is a drop node ora pass-through node, in either case it can serve as a source node forthe next signal hop. Also, a destination node can be a regenerationnode, where the data signal is regenerated so it can be transmitted tosubsequent nodes with adequate properties (e.g., sufficient strength,signal-to-noise ratio, etc.). Note that these functions are not mutuallyexclusive. A given destination node might function as a drop node, aregeneration node, and a source node for another hop. Since this exampleembodiment relates to broadcast data, each destination node is also adrop node.

Referring to FIG. 1, after node S1 is designated as the primary sourcenode, the possible destination nodes are S2 and S3. S4 is not considereda possible destination node, because it is a glass node having nonetwork equipment. However, there are two routes to node S3 from nodeS1: via link L1/3 and via the pair of links L1/4 and L3/4. Informationis displayed on display 5 to indicate the possible destination nodes. Inthis example embodiment, the information is displayed in the form of adrop-down menu 15. Menu 15 includes a listing of all possibledestination nodes for the currently designated source node, but excludesglass nodes. Where there is more than one route from the source node toa given possible destination node, menu 15 includes multiple entries forthe given possible destination node, with each entry including adesignation of one of the possible routes. As shown in FIG. 1,therefore, drop-down menu 15 includes entries for S2, S3-L1/3, andS3-L1/4, L3/4.

Alternatively, the information indicating possible destination nodescould be output by highlighting nodes and links on display 5. Forexample, possible destination nodes and the routes to them from thesource node could be highlighted in color, and multiple colors could beused if there is more than one route to a possible destination node.

In the example embodiment, a user can designate a node as a destinationnode by clicking on one of the entries listed in menu 15. After adestination node is designated, the user can designate the node as adrop node by clicking on soft button 40. Also, when a destination nodeis designated, optical characteristics for the route are updated basedon stored information regarding the network links. In the exampleembodiment, the optical characteristics are updated based on the opticalsignal-to-noise ratio (OSNR). In particular, since the properties of thesignal are known at the source node and the properties of the link orlinks in the route are known, the OSNR at the designated destinationnode, after traversing the route, can be calculated. Alternatively,other characteristics such as polarization mode dispersion, chromaticdispersion, attenuation, or a combination of plural characteristics canbe updated. Further, an updated value for the characteristic can beoutput as a raw value, or the updated value can be compared to one ormore thresholds and the result of the comparison or comparisons can beoutput.

In this example embodiment, an updated OSNR is compared to twothresholds and the results are output by displaying the comparisonresults in area 60 of display 5. First, the OSNR is compared to athreshold that indicates whether the data signal will have acceptableproperties (e.g., a sufficiently high OSNR) if the signal is routed tothe designated destination node using the designated route. If the OSNRvalue is below the threshold, then the user should either (i) designatean upstream node as a regeneration node, in order to regenerate thesignal with sufficient strength that it can be satisfactorily routedalong the designated route to the designated destination node, or (ii)if an alternative route is available to the destination node, designatethe alternative route and view the results of the updated opticalcharacteristics.

Next, the OSNR is compared to a second threshold that indicates whetherthe data signal will have an acceptable value if it is transmitted fromthe designated destination node to a further node. If the OSNR is belowthe threshold value, than the user should either (i) designate thedesignated destination node as a regeneration node, or (ii) if analternative route is available to the designated destination node,designate the alternative route and view the results of the updatedoptical characteristics. FIG. 1 illustrates how the result of thecomparison of the OSNR to the two threshold values may be displayed.

Thus, the user uses the updated optical characteristics to determinewhether (i) the designated destination node should be designated as aregeneration node, (ii) an upstream node should be designated as aregeneration node, or (iii) an alternative route (if one exists) shouldbe designated to reach the destination node. By updating the opticalcharacteristics based on a designated destination node, the user caninteractively provision routes while taking into consideration factorsbeyond those conventionally used by automatic routing algorithms(shortest distance, minimum cost, fewest links, etc.). For example, theuser can select alternative routes where multiple routes are available,in an effort to minimize the required number of regeneration nodes.Further, if the user has a choice among alternative routes to a possibledestination, the user can take other factors into account wheninteractively selecting a route. For example, the user can considerwhether a route involving a particular node or link should be avoidedbased on factors such as, for example, office power, current networkelement utilization, current span utilization, tariffs and other factorsrelating to geographical boundaries, poor fiber installations, highoutage areas, and potential “danger zones” where outages may occur dueto weather or other factors.

Referring again to FIG. 1, a user can designate node S2 from among thepossible destination nodes from source node S1. Since each node is to bea drop node in this example relating to a broadcast, the user designatesnode S2 as a drop node. Also, since there is only one route from S1 toS2, the user observes the updated optical characteristics information inarea 60 and makes any necessary designation of a node as a regenerationnode. Also, an indicator such as solid arrow 70 may be displayed, toindicate data flow from S1 to S2.

Since node S2 is now selected, node S2 becomes the current source nodefor determining the next hop. Possible destination nodes from node S2are displayed in menu 15. Those possible destination nodes will be nodesS5 and S3. The user can designate node S5 as the destination node,designate the node as a drop node, and make any necessary designation ofa regeneration node based on the updated optical characteristics. Eachtime the optical characteristics are updated, any previously designatedregeneration nodes are taken into account.

Next, the displayed possible destination nodes from node S5 will benodes S10 and S9. The user can designate node S10 as the destinationnode, designate node S10 as a drop node, and review the updated opticalcharacteristics information to make any necessary designation of aregeneration node. Since node S10 is a spur node, there are no furtherpossible destination nodes from node S10. Therefore, menu 15 willcontain no entries, and the optical characteristics information withrespect to the second threshold will indicate N/A.

The user can now go back to a previous node, e.g., node S5, and click onthat node again to designate it as the current source node. In thisexample embodiment, nodes that are already designated as drop nodes(i.e., a route to the node has already been provisioned), will beexcluded from the list of possible destination nodes. Therefore, menu 15will only include node S9 as a possible destination node. The user cancontinue the process of selecting source nodes, selecting a possibledestination node from those available from source node, designatingnodes as drop nodes, and designating nodes as regeneration nodes basedon the updated optical characteristics, until routes have beenprovisioned to all the intended drop nodes (in this case, all the nodeshaving network equipment).

In many cases, it is desirable to have a secondary source in case aproblem develops with a primary source of data transmission.Accordingly, the user can select soft button 30 and then designate anode as a secondary source, such as node S2. The user can then provisionroutes to each drop node from secondary source node S2 in a manner likethat described above for the primary source node.

With respect to the secondary source node, there are two conventionsadhered to in this example embodiment. First, any nodes designated asregeneration nodes while provisioning routes from the primary sourcenode are taken into consideration when updating the opticalcharacteristics of a route.

Second, in order to achieve diverse routing, data from the secondarysource node S2, which traverses a link used by data from the primarysource node S1, must traverse the link in the opposite direction. Putanother away, only one type of network traffic (Primary, from theprimary source node, or Secondary, from the secondary source node) mayflow in a specific direction on a given link. For example, referring toFIG. 1, node S1 is a possible destination from node S2, because the datafrom node S2 can travel to node S1 on link L1/2 in the oppositedirection from data traveling on that same link from node S1 to node S2.Also, node S3 is a possible destination node from node S2, because linkL2/3 was not used in provisioning routes from primary node S1. However,node S5 is not a destination node from node S2. Data from node S2 cannotuse link L2/5 because it would be traveling in the same direction asdata routed from primary source node S1. Further, there is noalternative route that does not pass through another node containingnetwork equipment. It is noted that in some cases a route cannot beprovisioned to certain nodes from the designated secondary source node.For example, there is only one link to a spur node such as node S110.

FIG. 2 illustrates network 10 with routes from the primary and secondarysource nodes indicated. Dotted arrows are used to designate routes fromthe secondary source node S2.

Information regarding the identification of each node and link in thenetwork, optical properties of the links, the routes provisioned betweennodes, the type of node (e.g., source, drop, regeneration, spur, or acombination), and the like can be stored in a memory. This informationcan be used to generate a report, which can be formatted appropriatelyand output to a display or printer for review by a user or for hardcopyarchiving. In addition, the information can be used to generate a billof materials, i.e., equipment necessary to implement the network, and/ora cost for the network. Further, the stored information can be comparedto other configurations of routes and regeneration nodes, to determinewhich configuration is less expensive.

In the example embodiment described above, each designated destinationnode was in turn used as the source node to determine the next hop,until no further possible destination nodes existed, and then a previousnode was returned to in order to provision routes along other paths.Alternatively, routes may first be provisioned for all possibledestination nodes from a given source node, before designating adestination node as a new source node. In other words, a “breadth-first”rather than a “depth-first” approach may be used.

FIG. 3 illustrates a process according to an example embodiment of thepresent invention. In block 300, information regarding a network, suchas that shown in FIG. 1, is displayed. In block 305, a designation of aprimary source node is received. For example, this designation may bereceived from a user interface.

Next, in block 310, possible destination nodes are determined from thedesignated source node, and information indicating the possibledestination nodes is output in block 315. For example, the informationmay be output as a drop-down menu like menu 15 shown in FIG. 1. Then, inblock 320, a designation of a destination node is received. If more thanone route is possible to the designated destination node, then thedesignation includes a designation of a particular route. (If there isonly one route, that route is implicitly included in the designation ofthe destination node.)

In block 325, information regarding optical characteristics is updatedbased on the designated destination node and the route to that node, aswell as stored optical characteristics of the nodes and links, and anydesignated regeneration nodes. The updated optical characteristics arecompared to two thresholds in block 330, and information related to theupdated optical characteristics—in this example, the result of thecomparison—is output in block 335. The information can be output bydisplaying it at a predetermined area of a display, for example. Byreviewing the information output in block 335, a user can determinewhether to designate a node as a regeneration node. The user can alsodesignate appropriate nodes as drop nodes. Accordingly, a designation ofa node as a drop node and/or a regeneration node may be received.

In block 340, the designated destination node is set as a new sourcenode, and in block 345 the possible destination nodes are determined forthe new designated source node. In block 350, a decision is made as towhether there are any possible destination nodes for the new sourcenode. If so, then the process returns to block 315 to output informationindicating the possible destination nodes. If it is decided in block 350that there are no possible destination nodes for the current sourcenode, then a decision is made in block 355 as to whether there are anyremaining nodes for which a route has not been provisioned (i.e., nodesthat have not been designated as drop nodes, in this broadcast example).If there are remaining nodes that need routes provisioned, then adesignation of a new source node is received in block 360 and flowreturns to block 310. If not, than a designation of a secondary sourcenode is designated in block 365 and flow returns to block 310.Processing is the same for the secondary source node, except that block310 takes into account routes provisioned for the primary source nodewhen determining possible destination nodes, so that data from thesecondary source node cannot traverse the same link in the samedirection, and block 325 takes into account nodes already designated asregeneration nodes when updating optical characteristics.

FIG. 4 illustrates an alternative example embodiment of the presentinvention. As described above with respect to the example embodiment inFIG. 1, information indicating possible destination nodes is output inthe form of a menu listing possible destination nodes. If there aremultiple routes possible to a given possible destination, there aremultiple entries for the given possible destination, each one includingan indication of one of the possible routes. Hence, a possibledestination and a particular route to that destination are selectedtogether. Alternatively, the destination can be selected first, and thena route to the destination selected separately.

As shown in FIG. 4, a designation of a primary source node is receivedin block 400. Then, possible destination nodes are determined in block405, and information indicating the possible destination nodes is outputin block 410. In this example embodiment, the output information isindicated by highlighting possible destination nodes on display 5,although a list of the destination nodes (without an indication ofspecific routes) could also be used. In block 415, a designation isreceived of a designated destination node. In this example embodiment,the designation may come from a user interface where a user uses a mouseto click on a highlighted possible destination node on display 5. Then,in block 420, possible routes to the designated destination node aredetermined, and in block 425 information is output to indicate thepossible routes. In this example embodiment, the information ishighlighting of the possible routes on display 5, although it could alsobe a list of routes. In block 430, optical characteristics are updatedfor each possible route to the designated destination node, and in block435 information is output relating to the updated opticalcharacteristics. For example, the information can be displayed adjacentto each respective possible route, or in table form with a display entrycorresponding to each possible route. Alternatively, the possible routehaving the best value for the optical characteristics could behighlighted or displayed in a different color.

A user can determine which possible route to the designated destinationis preferred, based on the information related to the updated opticalcharacteristics, and in block 340 a designation of a route from amongthe possible routes is received. The designation may be from a userinterface when a user uses a mouse to click on one of the highlightedpossible routes. The information regarding the updated opticalcharacteristics can then be displayed in area 60, and processing canproceed as in block 340 of FIG. 3, with further processing similar tothat of FIG. 3.

In the example embodiment of FIG. 4, the updated optical characteristicsare determined for each possible route, and information related to theupdated characteristics is displayed prior to selection of a particularpossible route. Alternatively, information regarding the possible routescan be output, and then after a designation of a particular route isreceived, the optical characteristics can be updated for the designatedroute and information regarding the updated optical characteristics canbe output.

FIG. 5 illustrates an example embodiment of an apparatus to provisionnetwork routes according to the present invention. As shown in FIG. 5,an apparatus 500 includes a display 505 and a user interface 510, suchas a mouse. Apparatus 500 also includes a memory 515 to storeinformation regarding network nodes, links, and routes. While memory 515is illustrated as a single memory, those skilled in the art willappreciate that it may include multiple memory devices, which may be ofdifferent types, and may provide memory for storing control programs andworking memory used during information processing and/or display.

FIG. 5 further includes a processor 520 to control the apparatus. Inthis example embodiment, processor 520 executes program code stored inmemory 515, which causes the apparatus to perform a process as describedwith respect to FIGS. 1 to 3. The program code may, for example, bestored in a read-only section of memory 515, be stored on a removablecomputer-readable medium and transferred to apparatus 500, or bedownloaded to apparatus via a communication link, e.g., via theinternet. Also, those skilled in the art that rather than a processor orcomputer executing program code, apparatus 500 could be controlled by anequivalent hardware circuit providing the same functions.

FIG. 6 illustrates an example embodiment of a process followed by a userto provision network routes, according to the present invention. Inblock 600, a user designates a primary source node. The designation maybe made, for example, by clicking on a symbol representing a node in adisplay of a network. In block 610, the user designates a destinationnode in a display of possible destination nodes from the designatedsource node. In this example embodiment, the designation is made byselecting an entry from a drop-down menu. If there is more than onepossible route to a given possible destination node, than the entries inthe drop-down menu will include both the possible destination node andan indication of a particular route. Alternatively, the designationcould be made by clicking on nodes and/or links in a display of thenetwork.

In block 615, the user designates the designated destination node as adrop node, if the signal is to be dropped at that node.

In block 620, the user designates a node as a regeneration node, basedon displayed information relating to updated optical characteristicsbased on the designated destination node. In this embodiment, thedisplayed information indicates the result of a comparison of theupdated optical characteristics to two thresholds. By reviewing thedisplayed information, the user can determine whether (i) the datasignal needs to be regenerated upstream in order to reach the designateddestination node using the designated route, and (ii) whether the datasignal needs to be regenerated at the designated destination node beforebeing sent on to another node.

In block 625, the process is repeated until routes have been provisionedfor all drop nodes. Then, in block 630, a secondary source node isdesignated and the process is repeated.

The above-described example embodiments have been explained with respectto a mesh network. Those skilled in the art will recognized that thepresent invention is not limited to a mesh network, but may also beapplied to a network of interconnected rings, other networks havingnodes with multiple degrees of connectivity, and other networks wherethere may be multiple possible routes between a source node and adestination node. Further, while the above-embodiments have beendiscussed in the context of routing broadcast traffic, and in particularin the context of dual source routing of broadcast data, those skilledin the art will appreciate that the present invention is not limited tobroadcast data. Also, while example embodiments have been describedwhere all possible destination nodes are determined from a designatedsource node, one skilled in the art will appreciate that not allpossible destination nodes need to be determined. For example,restrictions can be imposed that limit the possible destination nodes.For example, a user could set a limit of two links, so that the possibledestination nodes only include nodes that can be reached via two orfewer links.

Other variations and embodiments are also possible. Accordingly thescope of the invention is not intended to be limited to the specificexamples and embodiments presented above, but rather should bedetermined by reference to the claims appended hereto.

1. A method to provision routes in a network having a plurality ofnodes, comprising: (a) receiving a designation of a primary source node;(b) determining possible destination nodes from the designated sourcenode and outputting information indicating the possible destinationnodes; (c) receiving a designation of a destination node from among thepossible destination nodes; and (d) updating information regardingoptical characteristics based on a route from the source node to thedesignated destination node and outputting information related to theupdated optical characteristics.
 2. A method according to claim 1,further comprising: repeating (c) and (d) until there are no morepossible destination nodes for the designated source node.
 3. A methodaccording to claim 1, further comprising: repeating (b) through (d)using the designated destination node as a source node.
 4. A methodaccording to claim 1, wherein, when more than one route exists from thedesignated source node to a given possible destination node, the outputinformation indicating the possible destination nodes includesinformation indicating each possible route to the given possibledestination node.
 5. A method according to claim 4, wherein receiving adesignation of a destination node comprises receiving a designation of apossible destination node and a particular route to the designateddestination node, and the updating comprises updating informationregarding optical characteristics based on the particular route to thedesignated destination node.
 6. A method according to claim 1, whereinthe updating comprises updating information regarding at least one ofoptical signal-to-noise ratio, polarization mode, chromatic dispersion,and attenuation.
 7. A method according to claim 6, wherein the updatingcomprises comparing the updated optical characteristics to at least onethreshold and outputting information about the result of the comparison.8. A method according to claim 7, further comprising: receiving adesignation of a node as at least one of a drop node and a regenerationnode.
 9. A method according to claim 8, further comprising: generating areport including, for each node in the network, the type of node and theroutes used to the node.
 10. A method according to claim 8, furthercomprising: generating information regarding at least one of (i) thecost to implement a network using the designated routes and (ii) a billof materials needed to implement a network using the designated routes.11. A method according to claim 1, further comprising: receiving adesignation of a secondary source node; and repeating (b)-(d) based onthe secondary source node.
 12. A method according to claim 11, wherein,when determining possible destination nodes, data from the secondarysource node is prohibited from traversing a link in the same directionas data from the primary source node.
 13. A method according to claim11, wherein the updating of optical characteristics while provisioningroutes for the secondary source node takes into consideration nodes thathave been designated as regeneration nodes while provisioning routes forthe primary source node.
 14. A method to provision routes in a networkhaving a plurality of nodes, comprising: receiving a designation of asource node; determining possible destination nodes from the designatedsource node and outputting information indicating the possibledestination nodes; receiving a designation of a destination node fromamong the possible destination nodes; determining possible routes fromthe source node to the designated destination node and outputtinginformation indicating the possible routes; updating informationregarding optical characteristics for each possible route from thesource node to the designated destination node and outputtinginformation related to the optical characteristics; and receiving adesignation of a route from among the possible routes to the destinationnode.
 15. An apparatus to provision routes in a network, comprising: amemory to store information regarding a plurality of network nodes andlinks connecting network nodes; a display to display informationregarding the plurality of network nodes and the links connecting thenetwork nodes; a user interface to input user designations; and aprocessor to control the apparatus to (i) receive a designation from theuser interface indicating a source node, (ii) determine possibledestination nodes from the designated source node, (iii) displayinformation regarding the possible destination nodes, (iv) receive adesignation from the user interface indicating a destination nodeselected from among the possible destination nodes, (v) updateinformation regarding optical characteristics based on the designateddestination node and the stored information regarding links betweennetwork nodes, and (vi) display information related to the updatedoptical characteristics.
 16. An apparatus according to claim 15, whereinthe processor controls the display to display symbols representing eachnetwork node, each link connecting network nodes, and a designated routebetween a source node and a destination node.
 17. An apparatus accordingto claim 15, wherein the processor displays information regardingpossible destination nodes by displaying a drop-down menu listingpossible destination nodes for the designated source node.
 18. Anapparatus according to claim 17, wherein, when there are multiplepossible routes from a source node to a given possible destination node,the given possible destination node is listed multiple times in thedrop-down menu, with each listing including an indication of one of thepossible routes.
 19. An apparatus according to claim 18, wherein theprocessor receives a designation of a possible destination node and apossible route and updates the information regarding opticalcharacteristics based on the designated destination node and thedesignated route.
 20. An apparatus according to claim 15, wherein theprocessor displays information related to the updated opticalcharacteristics by comparing the updated optical characteristics to atleast one threshold and displaying the result of the comparison.
 21. Acomputer program embodied in a computer-readable storage medium, theprogram comprising code to control an apparatus to: receive adesignation indicating a source node among a plurality of network nodes;determine possible destination nodes from the designated source node;display information regarding the possible destination nodes; receive adesignation indicating a destination node selected from among thepossible destination nodes; update information regarding opticalcharacteristics based on the designated destination node and storedinformation regarding links between network nodes; and displayinformation related to the updated optical characteristics.
 22. A methodto provision routes in a network having a plurality of nodes,comprising: designating a primary source node; designating a destinationnode in a display of possible destination nodes from the designatedprimary source node; and designating a node as a regeneration node,based on displayed information concerning optical characteristicsupdated based on the designated destination node.
 23. A method accordingto claim 22, wherein designating a primary source node comprisesselecting a symbol corresponding to a node on a display, and designatinga destination node comprises selecting a possible destination node froma displayed drop-down menu listing the possible destination nodes.
 24. Amethod according to claim 23, wherein, when there is more than onepossible route from the primary source node to a given possibledestination node, designating a destination node comprises designatingthe given possible destination node and a particular route to the givenpossible destination node from the drop-down menu.
 25. A methodaccording to claim 22, further comprising: designating a secondarysource node; designating a possible destination node from a display ofpossible destination nodes from the secondary source node; anddesignating a node as a regeneration node, based on displayedinformation concerning optical characteristics updated based on thedesignated destination node.